1. Field of the Invention
The present invention relates to a method of producing a bead inductor and an apparatus for producing a molded body to be included in a bead inductor.
2. Description of the Related Art
Bead inductors are used as anti-noise or noise elimination components, particularly in microprocessors or other similar devices, in which a large amount of current needs is supplied and transmitted. A bead inductor consisting of a conductor coil embedded in rubber or resin material containing magnetic powder (such as ferrite powder) is known. In general, in forming this type of bead inductor, a conductor coil is embedded in resin or rubber material via injection molding or the like, whereby a molded body is formed. Then, both ends of the molded body are cut to expose both ends of the coil embedded in the resin or the rubber material. Thereafter, metallic caps which define external terminal electrodes, are mounted on the exposed coil ends, for example, by using an electrically conductive, resinous paste or via spot welding.
FIGS. 6 and 7 are sectional views illustrating a method of producing a molded body used to form a bead inductor via injection molding. It is noted that the subject matter shown in FIGS. 6 and 7 and the description thereof contained herein has not yet been published.
Referring to FIG. 6, an injection mold, used to form a molded body to be included in a bead inductor, includes an upper mold portion 1 and a lower mold portion 2. A cavity 3 in which resin is molded is formed in the upper mold portion 1. A space 3a provided to form a projecting portion on the molded body is formed above the cavity 3. At the lower mold portion 2, a spacer pin 4 is arranged to be located within the cavity 3 when the lower mold portion 2 and the upper mold portion 1 are fitted together. A gate la used to supply molten resin into the cavity 3 is formed in the upper mold portion 1.
When a molded body used for forming a bead inductor is produced using the mold of FIG. 6, a conductor coil, which is formed by winding into a spiral or other shaped configuration, a metallic wire, such as a copper wire, coated with an insulating material, such as polyester resin, is inserted onto the spacer pin 4. Then, molten resin containing magnetic powder, such as ferrite powder, is injected into the cavity 3 from the gate 1a, causing an outer portion to be formed outside of the conductor coil inserted onto the spacer pin 4.
FIG. 7 is a sectional view showing a state in which the outer portion is formed outside of a conductor coil 5 using the above-described method. As shown in FIG. 7, the conductor coil 5 is embedded in the molded body 6, and the spacer pin 4 is located inside of the conductor coil 5. This spacer pin 4 is pulled out of the molded body 6 in order to allow formation of an inner portion located inside of the conductor coil 5.
FIGS. 8A, 8B, and 8C are sectional views illustrating the steps carried out to form an inner portion inside of the conductor coil 5 via molding. FIG. 8A illustrates the molded body 6, with the upper mold portion 1 and the lower mold portion 2 being separated from each other as a result of moving the upper mold portion 1 upward from its position shown in FIG. 7. The spacer pin 4 is disposed in the molded body 6, and is mounted on the lower mold portion 2. The molded body 6 has a protruding portion 6a at the top portion thereof. The protruding portion 6a is removed by cutting or a similar process, thereby, allowing the spacer pin 4 in the molded body 6 to be pulled upward and removed therefrom.
FIG. 8B illustrates a state after removal of the spacer pin 4 by the above-described method. A space 6b is formed in the molded body 6 as a result of the removal of the spacer pin 4. With the space 6b being formed in the molded body 6, the upper mold portion 1 is fitted onto the lower mold portion 2 again, as shown in FIGS. 6 and 7. From the gate 1a, molten resin is supplied into the mold so as to flow into the space 6b, causing an inner portion to be formed inside of the conductor coil 5.
FIG. 8C is a sectional view illustrating a state after formation of an inner portion inside of the conductor coil 5 via molding. A protruding portion 6c corresponding to a configuration of the space 3a of FIG. 6 is formed at the top portion of the molded body 6, while a protruding portion 6d is formed at the bottom portion of the molded body 6 so as to be disposed in the space in the lower mold portion 2 where the spacer pin 4 was inserted.
FIG. 9 is a sectional view of the molded body 6 formed by the above-described molding method. The conductor coil 5 is embedded in the molded body 6. The protruding portion 6c is formed at the top portion of the molded body 6, while the protruding portion 6d is formed at the bottom portion of the molded body 6. By cutting the molded body 6, using, for example, a dicing saw, along cutting lines Axe2x80x94A and Bxe2x80x94B, the ends of the conductor coil 5 in the molded body 6 are exposed. Metallic caps are electrically connected and mounted to the exposed ends of the conductor coil 5, for example, by using electrically conductive resinous paste or via spot welding.
FIGS. 10 and 11 are a side view and a plan view illustrating a bead inductor having metallic caps mounted thereon. One end 5a of the conductor coil 5 is electrically connected to a metallic cap 7, while the other end 5b of the conductor coil 5 is electrically connected to a metallic cap 8. The metallic caps 7 and 8 are used as external terminal electrodes.
In the above-described bead inductor and method of forming thereof, the spacer pin is removed after formation of the outer portion located outside of the conductor coil via molding. To remove the spacer pin, it is necessary to open the mold and to cut the protruding portion at the top portion of the molded body. This makes it difficult to automate and simplify the injection molding cycle. Therefore, when the conventional bead inductor production method is used, molded bodies cannot be formed with high productivity.
To overcome the problems described above, preferred embodiments of the present invention provide a method of manufacturing a bead inductor and a bead inductor molded body producing apparatus, which achieve improved and highly efficient production of bead inductor molded bodies having a conductor coil embedded therein.
According to a first aspect of preferred embodiments of the present invention, there is provided a method of producing a bead inductor, in which a molded body having a hollow core conductor coil embedded in rubber or resin material containing magnetic powder is formed, and in which both ends of the conductor coil in the molded body are exposed to electrically connect external terminal electrodes to both of the exposed ends of the conductor coil, the method including the steps of forming an outer portion outside of the conductor coil via molding, by disposing the conductor coil in a cavity of a mold having a first gate and a second gate formed therein, disposing a spacer pin which passes through the core of the conductor coil and extends up to the second gate to close the second gate, and supplying the rubber or the resin material containing magnetic powder into the mold cavity from the first gate and forming the molded body with the conductor coil embedded therein, by, after the formation of the outer portion outside of the conductor coil, closing the first gate, pulling the spacer pin out of the mold cavity, and supplying from the second gate the rubber or the resin material containing magnetic powder into a space formed as a result of the removal of the spacer pin so as to extend through the core of the conductor coil, in order to form an inner portion inside of the conductor coil.
In such a case, after the formation of the outer portion outside of the conductor coil, the spacer pin is pulled out. When the outer portion is formed outside of the conductor coil via molding, the spacer pin is disposed so as to pass through the core of the conductor coil and to extend up to the second gate to close the second gate. When the spacer pin is pulled out, a space which extends through the core of the conductor coil from the second gate is formed. From the second gate, resin or rubber material is supplied into the space located inside of the conductor coil. In the first aspect, the outer portion does not have to be removed after the formation of the outer portion outside of the conductor coil, so that the next step of forming an inner portion inside of the conductor coil can be carried out with the outer portion being disposed in the mold cavity.
The mold may have an accommodating hole for accommodating the spacer pin therein. When the outer portion is formed outside of the conductor coil via molding, a portion of the spacer pin may be pushed out of the accommodating hole and pushed into the mold cavity. On the other hand, when the inner portion is formed inside of the conductor coil via molding, the spacer pin may be pulled out so that a portion of the spacer pin is accommodated in the accommodating hole.
In such a case, since an accommodating hole may be formed in the mold to allow insertion and removal of the spacer pin into and out of the cavity, it possible to provide a an excellent and greatly improved production method which allows automation and simplification of the molding process.
The mold may include an upper mold portion and a lower mold portion.
In such a case, since the mold may include an upper mold portion and a lower mold portion, it possible to stably and easily insert the conductor coil into the mold.
When the mold includes an upper mold portion and a lower mold portion, the spacer pin may be divided into a first spacer pin portion and a second spacer pin portion, the first spacer pin portion having a shape which fits into the accommodating hole formed in the lower mold portion, and the second spacer pin portion having a shape which fits into the second gate formed in the upper mold portion. In forming the outer portion outside of the conductor coil via molding, a portion of the first spacer pin portion and a portion of the second spacer pin portion of the spacer pin may be pushed into the mold cavity from the accommodating hole and from the second gate, respectively, in order to bring the first spacer pin portion and the second spacer pin portion into contact with each other, whereby the spacer pin is formed so as to pass through the mold cavity. On the other hand, in forming the inner portion inside of the conductor coil via molding, the first spacer pin portion may be pulled out so that a portion thereof is accommodated in the accommodating hole formed in the lower mold portion, and the second spacer pin portion may be pulled out and removed out of the mold from the second gate.
In such a case, the spacer pin may be divided into a first spacer pin portion and a second spacer pin portion and formed so as to pass through the mold cavity. In forming the outer portion outside of the conductor coil via molding, a spacer pin may be formed by pushing a portion of the first spacer pin portion and a portion of the second spacer pin portion into the mold cavity and causing the first and second spacer pin portions to contact each other. Thus, compared to the case where one spacer pin is pushed into the mold cavity from the lower mold portion so that the spacer pin passes through the mold cavity and is inserted into the second gate formed in the upper mold portion to close it, the upper mold portion and the lower mold portion can be easily designed so that they are, for example, positioned precisely with respect to each other.
When the spacer pin is divided into a first spacer pin portion and a second spacer pin portion and formed so as to pass through the mold cavity, the first gate may be formed in the upper mold portion.
In such a case, since the first gate may be formed in the upper mold portion, it is much easier to design, for example, a molding machine or a mold.
In the case where the spacer pin is divided into a first spacer pin portion and a second spacer pin portion and formed so as to pass through the mold cavity, or in the case where the first gate is formed in the upper mold portion, when the conductor coil is disposed in the mold cavity, a portion of the first spacer pin portion may be pushed out of the accommodating hole, and the core of the conductor coil may be mounted onto the first spacer pin portion in order to position the conductor coil in the cavity.
In such a case, since the conductor coil may be positioned by inserting the core of the conductor coil onto the first spacer pin portion, it is much easier to design a molding machine.
In forming the inner portion inside of the conductor coil via molding, the first gate may be closed by inserting a closing pin into the first gate.
In such a case, since the first gate may be closed by inserting a closing pin into the first gate, the structure of, for example, a molding machine or a mold is greatly simplified.
When the first gate is closed by inserting a closing pin, after the formation of the inner portion inside of the conductor coil via molding, the molded body may be ejected from the mold by pushing a portion of the closing pin out of the first gate and inserting the portion of the closing pin into the mold cavity.
In such a case, since the molded body may be ejected from the mold via the closing pin used to close the first gate, the structure of, for example, a molding machine or a mold can be greatly simplified, and the molded body can be automatically ejected after molding.
In the case where the first gate is closed by inserting a closing pin into it or in the case where the molded body is ejected from the mold by using the closing pin used to close the first gate, during the formation of the inner portion inside of the conductor coil via molding, the second spacer pin portion which is removed out of the mold may be used as the closing pin for insertion into the first gate.
In such a case, since the second spacer pin portion may be used as the closing pin, the structure of, for example, a molding machine or a mold can be greatly simplified.
A molding cycle including the steps of inserting the conductor coil into the mold cavity, forming the outer portion outside of the conductor coil via molding, forming the inner portion inside of the conductor coil via molding, and ejecting the molded body from the mold may be repeated by automatic control.
In such a case, since the molding process carried out to form a bead inductor molded body may be automated, it is possible to increase operation efficiency of a molding machine, and to mass-produce molded bodies economically.
According to another aspect of preferred embodiments of the present invention, there is provided an apparatus for producing a molded body to be included in a bead inductor, in which the molded body is formed in a mold cavity via injection molding when producing the bead inductor by electrically connecting external terminal electrodes to both ends of a hollow core conductor coil disposed in the molded body formed by embedding the hollow core conductor coil in rubber or resin material containing magnetic powder, the apparatus including an upper mold portion having a first gate and a second gate arranged to allow rubber or the resin material containing magnetic powder to be supplied into the mold cavity, a lower mold portion which is fitted to the upper mold portion to define the mold cavity, the lower mold portion having an accommodating hole in a portion thereof located at a position in correspondence with a substantially center portion of the mold cavity, a first spacer pin portion arranged to be movably disposed in the accommodating hole in the lower mold portion, a second spacer pin portion arranged to be movably disposed in the second gate in the upper mold portion, and a closing pin arranged to be movably disposed in the first gate in the upper mold portion, wherein after insertion of the core of the conductor coil onto the first spacer pin portion, a portion of which first spacer pin portion is upwardly pushed out of the accommodating hole formed in the lower mold portion, the upper mold portion and the lower mold portion are fitted together to define the cavity used for the injection molding, the second spacer pin portion is pushed downward so that a portion thereof is pushed out of the second gate in the upper mold portion in order to bring the second spacer pin portion into contact with the first spacer pin portion, whereby a spacer pin which passes through the cavity is formed. In this state, the rubber or the resin material containing magnetic powder is supplied into the cavity from the first gate to form an outer portion outside of the conductor coil the molding. After the molding, the first spacer pin portion is pulled out so that a portion thereof is accommodated in the accommodating hole formed in the lower mold portion, and the second spacer pin portion is pulled out and removed out of the mold from the second gate. A closing pin is inserted into the first gate to close the first gate. From the second gate, the rubber or the resin material containing magnetic powder is supplied into a space formed inside of the conductor coil, by pulling out the first spacer pin portion and the second spacer pin portion, whereby the molded body having the conductor coil embedded therein is formed.
In such a case, after the formation of the outer portion outside of the conductor coil via molding, an inner portion can be formed inside of the conductor coil, without taking out the outer portion from the mold. This makes it possible to produce molded bodies efficiently and easily.
In the above-described device, the closing pin may be used as the second spacer pin portion.
In such a case, the structure of, for example, an injection mold or a mold can be greatly simplified. This makes it possible to automate the molding process and to reduce molding costs.
When the apparatus according to preferred embodiments of the present invention is used or when the closing pin is used as the second spacer pin portion, after the formation of the molded body with the conductor coil embedded therein, the upper mold portion and the lower mold portion which have been fitted together may be separated from each other, and the closing pin may be moved downward to push out and eject the molded body from the cavity.
In such a case, since the molded body may be pushed out of and ejected from the cavity by moving the closing pin downward, the molded body can be easily taken out, and the molding process can be automated.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.